Carrier sense multiple access (CSMA) is a media access control (MAC) protocol in which a node verifies the absence of other traffic before transmitting on a shared transmission medium, such as an electrical bus or a band of electromagnetic spectrum. The term “carrier sense” indicates that a transmitter uses feedback from a receiver that detects a carrier wave before trying to transmit (e.g., attempting to detect the presence of an encoded signal from another station before attempting to transmit) such that when a carrier is sensed the transmitter may wait for completion of the transmission that is currently in progress before initiating a new transmission. The term “multiple access” indicates that multiple terminals send and receive traffic via the transmission medium. CSMA collision avoidance (CSMA/CA) is used to improve the performance of CSMA by attempting to be less greedy with the transmission medium by deferring transmission for a random interval if another ongoing transmission is sensed on the medium.
In general, multi-hop wireless networks have been considered a difficult modeling problem, because transmissions from a given node may affect the medium access of one or more other nodes in an intricate way. For example, in a CSMA/CA wireless network, a non-transmitting node that detects an ongoing transmission by a transmitting node is expected to remain silent at least until the transmitting node has finished the transmission. While this silence of the non-transmitting node may prevent a collision that is caused by the non-transmitting node, the silence by the non-transmitting node may also be interpreted by neighboring nodes of the non-transmitting node as an indication that the medium is idle and, thus, may trigger new transmissions by one or more of the neighboring nodes.